backends/vhost-user.c

   1 /*
   2  * QEMU vhost-user backend
   3  *
   4  * Copyright (C) 2018 Red Hat Inc
   5  *
   6  * Authors:
   7  *  Marc-André Lureau <marcandre.lureau@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13
  14 #include "qemu/osdep.h"
  15 #include "hw/qdev.h"
  16 #include "qapi/error.h"
  17 #include "qapi/qmp/qerror.h"
  18 #include "qemu/error-report.h"
  19 #include "qom/object_interfaces.h"
  20 #include "sysemu/vhost-user-backend.h"
  21 #include "sysemu/kvm.h"
  22 #include "io/channel-command.h"
  23 #include "hw/virtio/virtio-bus.h"
  24
  25 static bool
  26 ioeventfd_enabled(void)
  27 {
  28     return kvm_enabled() && kvm_eventfds_enabled();
  29 }
  30
  31 int
  32 vhost_user_backend_dev_init(VhostUserBackend *b, VirtIODevice *vdev,
  33                             unsigned nvqs, Error **errp)
  34 {
  35     int ret;
  36
  37     assert(!b->vdev && vdev);
  38
  39     if (!ioeventfd_enabled()) {
  40         error_setg(errp, "vhost initialization failed: requires kvm");
  41         return -1;
  42     }
  43
  44     if (!vhost_user_init(&b->vhost_user, &b->chr, errp)) {
  45         return -1;
  46     }
  47
  48     b->vdev = vdev;
  49     b->dev.nvqs = nvqs;
  50     b->dev.vqs = g_new(struct vhost_virtqueue, nvqs);
  51
  52     ret = vhost_dev_init(&b->dev, &b->vhost_user, VHOST_BACKEND_TYPE_USER, 0);
  53     if (ret < 0) {
  54         error_setg_errno(errp, -ret, "vhost initialization failed");
  55         return -1;
  56     }
  57
  58     return 0;
  59 }
  60
  61 void
  62 vhost_user_backend_start(VhostUserBackend *b)
  63 {
  64     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(b->vdev)));
  65     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
  66     int ret, i ;
  67
  68     if (b->started) {
  69         return;
  70     }
  71
  72     if (!k->set_guest_notifiers) {
  73         error_report("binding does not support guest notifiers");
  74         return;
  75     }
  76
  77     ret = vhost_dev_enable_notifiers(&b->dev, b->vdev);
  78     if (ret < 0) {
  79         return;
  80     }
  81
  82     ret = k->set_guest_notifiers(qbus->parent, b->dev.nvqs, true);
  83     if (ret < 0) {
  84         error_report("Error binding guest notifier");
  85         goto err_host_notifiers;
  86     }
  87
  88     b->dev.acked_features = b->vdev->guest_features;
  89     ret = vhost_dev_start(&b->dev, b->vdev);
  90     if (ret < 0) {
  91         error_report("Error start vhost dev");
  92         goto err_guest_notifiers;
  93     }
  94
  95     /* guest_notifier_mask/pending not used yet, so just unmask
  96      * everything here.  virtio-pci will do the right thing by
  97      * enabling/disabling irqfd.
  98      */
  99     for (i = 0; i < b->dev.nvqs; i++) {
 100         vhost_virtqueue_mask(&b->dev, b->vdev,
 101                              b->dev.vq_index + i, false);
 102     }
 103
 104     b->started = true;
 105     return;
 106
 107 err_guest_notifiers:
 108     k->set_guest_notifiers(qbus->parent, b->dev.nvqs, false);
 109 err_host_notifiers:
 110     vhost_dev_disable_notifiers(&b->dev, b->vdev);
 111 }
 112
 113 void
 114 vhost_user_backend_stop(VhostUserBackend *b)
 115 {
 116     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(b->vdev)));
 117     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
 118     int ret = 0;
 119
 120     if (!b->started) {
 121         return;
 122     }
 123
 124     vhost_dev_stop(&b->dev, b->vdev);
 125
 126     if (k->set_guest_notifiers) {
 127         ret = k->set_guest_notifiers(qbus->parent,
 128                                      b->dev.nvqs, false);
 129         if (ret < 0) {
 130             error_report("vhost guest notifier cleanup failed: %d", ret);
 131         }
 132     }
 133     assert(ret >= 0);
 134
 135     vhost_dev_disable_notifiers(&b->dev, b->vdev);
 136     b->started = false;
 137 }
 138
 139 static void set_chardev(Object *obj, const char *value, Error **errp)
 140 {
 141     VhostUserBackend *b = VHOST_USER_BACKEND(obj);
 142     Chardev *chr;
 143
 144     if (b->completed) {
 145         error_setg(errp, QERR_PERMISSION_DENIED);
 146         return;
 147     }
 148
 149     g_free(b->chr_name);
 150     b->chr_name = g_strdup(value);
 151
 152     chr = qemu_chr_find(b->chr_name);
 153     if (chr == NULL) {
 154         error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
 155                   "Chardev '%s' not found", b->chr_name);
 156         return;
 157     }
 158
 159     if (!qemu_chr_fe_init(&b->chr, chr, errp)) {
 160         return;
 161     }
 162
 163     b->completed = true;
 164     /* could call vhost_dev_init() so early message can be exchanged */
 165 }
 166
 167 static char *get_chardev(Object *obj, Error **errp)
 168 {
 169     VhostUserBackend *b = VHOST_USER_BACKEND(obj);
 170     Chardev *chr = qemu_chr_fe_get_driver(&b->chr);
 171
 172     if (chr && chr->label) {
 173         return g_strdup(chr->label);
 174     }
 175
 176     return NULL;
 177 }
 178
 179 static void vhost_user_backend_init(Object *obj)
 180 {
 181     object_property_add_str(obj, "chardev", get_chardev, set_chardev, NULL);
 182 }
 183
 184 static void vhost_user_backend_finalize(Object *obj)
 185 {
 186     VhostUserBackend *b = VHOST_USER_BACKEND(obj);
 187
 188     g_free(b->dev.vqs);
 189     g_free(b->chr_name);
 190
 191     vhost_user_cleanup(&b->vhost_user);
 192     qemu_chr_fe_deinit(&b->chr, true);
 193 }
 194
 195 static const TypeInfo vhost_user_backend_info = {
 196     .name = TYPE_VHOST_USER_BACKEND,
 197     .parent = TYPE_OBJECT,
 198     .instance_size = sizeof(VhostUserBackend),
 199     .instance_init = vhost_user_backend_init,
 200     .instance_finalize = vhost_user_backend_finalize,
 201     .class_size = sizeof(VhostUserBackendClass),
 202 };
 203
 204 static void register_types(void)
 205 {
 206     type_register_static(&vhost_user_backend_info);
 207 }
 208
 209 type_init(register_types);